Re: The word from the OED

: : : : I presume some people have bastardised this saying using DICE instead of die ..

: : : : .. is this to do with engineering ..

: : : Actually, "die" in this case doesn't refer to gaming cubes (dice, in the plural) at all. It refers to pieces used in manufacturing for cutting, stamping, or forming material (usually metal). These things tend to be big, heavy, metal items and their straight edges tend to remain that way.

: : The die that is one member of a pair of dice* has to be straight-not weighted-in order to work properly, too.

: : *As Ambrose Bierce noted in "The Devil's Dictionary," "die" is "the singular of 'dice.' We seldom hear the word, because there is a prohibitory proverb, 'Never say die.' At long intervals, however, some one says: 'The die is cast,' which is not true, for it is cut."

: The Phrase Finder lists the origin of 'The die has been cast' as:
: 'The die here is a dice. Julius Caesar is supposed to have said this when crossing the Rubicon.'

: However, my understanding was that 'die' in this case refers to the die used for forming material, and that 'cast' here does not mean 'throw' but rather 'to form (molten metal etc.) into a particular shape by pouring into a mold'. So basically once the metal has been poured into the die it will set pretty quickly, and the shape (outcome) will be fixed.

: Can anybody provide a reference to confirm one meaning/origin or the other?

The Oxford English Dictionary (Compact Edition, 1971) answers both questions. It defines the phrase "The die is cast" as "the decisive step is taken; the course of action is irrevocably decided." It also says: "In comparisons: as smooth, true, straight as a die." Both quotations come from the OED's discussion of "die," the gaming cube (plural "dice"), not its discussion of "die," the device used in manufacturing (plural "dies").